7,772 research outputs found
Effect of a rigid ankle-foot orthosis on hamstring length in children with hemiplagia
Eighteen children with hemiplegia, mean age 8 years 5
months, underwent gait analysis and musculoskeletal
modelling using specially designed software. The maximum
lengths of the hamstrings were determined for each child
walking in and out of an ankle–foot orthosis (AFO). The
muscles were deemed to be short if shorter than the normal
average – 1SD. In bare feet 8 participants had short medial
hamstrings with a higher proportion of these in the less
involved individuals. All participants showed an increase in
maximum hamstring length when wearing an AFO. In all but
one child this was sufficient to restore hamstring length to
within normal limits. These finding suggest that hamstring
pathology in hemiplegic gait is usually secondary to more
distal lower limb pathology
The metal-insulator transition in disordered systems: a new approach to the critical behaviour
In the most popular approach to the numerical study of the Anderson
metal-insulator transition the transfer matrix method is combined with
finite-size scaling ideas. This approach requires large computer resources to
overcome the statistical fluctuations and to accumulate data for a sufficient
range of different values of disorder or energy. In this paper we present an
alternative approach in which the basic transfer matrix is extended to
calculate the derivative with respect to disorder. By so doing we are able to
concentrate on a single value of energy or disorder and, potentially, to
calculate the critical behaviour much more efficiently and independently of the
assumed range of the critical regime. We present some initial results which
illustrate both the advantages and the drawbacks of the method.Comment: 13 pages, 9 figure
On the consistency of ratings and bond market yields
We study the consistency of the credit-risk orderings implicit in ratings and bond market yields. By analyzing errors in term structure estimates for bonds with particular ratings, we show that for significant periods, a quarter of some categories of high credit quality bonds are rated in a manner that is inconsistent with their pricing. Adjusting for economic determinants of spreads (tax, liquidity and risk premiums) and allowing for the dynamic adjustment of ratings and spreads largely eliminates the inconsistencies, however. JEL Nos: C25, G21, G33
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Behaviour of moist and saturated sand during shock and release
Relatively little is known about the changes that occur in the shock compaction and release of granular matter with varying levels of moisture. Here, we report a series of plate impact experiments giving shock Hugoniot and release data for a well characterized sand at dry, 10% moist, and saturated water contents. The results reveal that at low moisture content the shock impedance is slightly reduced, while the release remains predominantly inelastic. Close to saturation, much more substantial changes occur: the shock impedance stiffens substantially, the Hugoniot appears to split into two branches, and the release becomes almost completely elastic. We discuss mechanisms underpinning these changes in behavior.This work was supported through the Force Protection Engineering research programme led by QinetiQ Plc. on behalf of DSTL.This is the author accepted manuscript. The final version is available from AIP via http://dx.doi.org/10.1063/1.493468
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The significance of grain morphology and moisture content on the response of silica sand to ballistic penetration
The dynamic response of sand is of interest for a wide range of applications, from civil engineering to asteroid impact, in addition to defense and industrial processes. Granular dynamics are controlled by a complex network of intergrain force chains; yet, our understanding of how grain morphology, moisture, rate, and loading geometry affect the response to rapid compaction remains limited. Here, we show how just 1% moisture can significantly reduce penetration resistance in silica sand, while smoother-grained material—with a similar bulk density, grain size, and mineralogy—exhibits markedly improved stopping power. Cylindrical targets are impacted by spherical steel projectiles, with Digital Speckle Radiography employed to determine both the penetration depth and the sand bed displacement at a series of incremental time steps after impact. The results provide substantial insight into how slight adjustments to grain-grain contact points can affect the bulk dynamic response of brittle granular materials.</jats:p
Calmodulin Binds a Highly Extended HIV-1 MA Protein That Refolds Upon Its Release
Calmodulin (CaM) expression is upregulated upon HIV-1 infection and interacts with proteins involved in viral processing, including the multifunctional HIV-1 MA protein. We present here the results of studies utilizing small-angle neutron scattering with contrast variation that, when considered in the light of earlier fluorescence and NMR data, show CaM binds MA in an extended open-clamp conformation via interactions with two tryptophans that are widely spaced in sequence and space. The interaction requires a disruption of the MA tertiary fold such that MA becomes highly extended in a long snakelike conformation. The CaM-MA interface is extensive, covering ∼70% of the length of the MA such that regions known to be important in MA interactions with critical binding partners would be impacted. The CaM conformation is semiextended and as such is distinct from the classical CaM-collapse about short α-helical targets. NMR data show that upon dissociation of the CaM-MA complex, either by the removal of Ca2+ or increasing ionic strength, MA reforms its native tertiary contacts. Thus, we observe a high level of structural plasticity in MA that may facilitate regulation of its activities via intracellular Ca2+-signaling during viral processing. © 2012 Biophysical Society
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Characterisation of the impact response of energetic materials: Observation of a low-level reaction in 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105)
Time resolved and integrated diagnostics including high speed photography, mass and optical spectroscopy, and optical-radiometry used to study impact response of high explosives in far more detail than possible with conventional sensitiveness tests.The authors wish to acknowledge the funding and provision of samples for this research by AWE plc.This is the author accepted manuscript. The final version is available from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C6RA03096
Four Cultural Narratives for Managing Social-ecological Complexity in Public Natural Resource Management
This is the final version. Available on open access from Springer via the DOI in this recordData availability: The data that comprised this research is stored at the UK Data Service but safeguarded due to its sensitive nature.Public Natural Resource Management (NRM) agencies operate in complex social-ecological domains. These complexities proliferate unpredictably therefore investigating and supporting the ability of public agencies to respond effectively is increasingly important. However, understanding how public NRM agencies innovate and restructure to negotiate the range of particular complexities they face is an under researched field. One particular conceptualisation of the social-ecological complexities facing NRM agencies that is of growing influence is the Water-Energy-Food (WEF) nexus. Yet, as a tool to frame and understand those complexities it has limitations. Specifically, it overlooks how NRMs respond institutionally to these social-ecological complexities in the context of economic and organisational challenges-thus creating a gap in the literature. Current debates in public administration can be brought to bear here. Using an organisational cultures approach, this paper reports on a case study with a national NRM agency to investigate how they are attempting to transform institutionally to respond to complexity in challenging times. The research involved 12 elite interviews with senior leaders from Natural Resources Wales, (NRW) and investigated how cultural narratives are being explicitly and implicitly constructed and mobilised to this end. The research identified four distinct and sequential cultural narratives: collaboration, communication, trust, and empowerment where each narrative supported the delivery of different dimensions of NRW's social-ecological complexity mandate. Counter to the current managerialist approaches in public administration, these results suggest that the empowerment of expert bureaucrats is important in responding effectively to complexity.Economic and Social Research Council (ESRC)Natural Resources Wale
CURIOS:Web-based presentation and management of linked datasets
A number of systems extend the traditional web and Web 2.0 technologies by providing some form of integration with semantic web data [1,2,3]. These approaches build on tested content management systems (CMSs) for facilitating users in the semantic web. However, instead of directly managing existing linked data, these systems provide a mapping between their own data model to linked datasets using an RDF or OWL vocabulary. This sort of integration can be seen as a read-only or write-only approach, where linked data is either imported into or exported from the system. The next step in this evolution of CMSs is a full integration with linked data: allowing ontology instances, already published as linked data, to be directly managed using widely used web content management platforms. The motivation is to keep data (i.e., linked data repositories) loosely-coupled to the tool used to maintain them (i.e., the CMS). In this poster, we extend [3], a query builder for SPARQL, with an update mechanism to allow users to directly manage their linked data from within the CMS. To make the system sustainable and extensible in future, we choose to use Drupal as the default CMS and develop a module to handle query/update against a triple store. Our system, which we call a Linked Data Content Management System (Linked Data CMS) [4], performs similar operations to those of a traditional CMS but whereas a traditional CMS uses a data model of content types stored in some relational database backend, a Linked Data CMS performs CRUD (create, read, update, and delete) operations on linked data held in a triple store. Moreover, we show how the system can assist users in producing and consuming linked data in the cultural heritage domain and introduce 2 case studies used for system evaluation
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